Our research focuses on the process and control of transcription by an oncogenic DNA virus, SV40, in monkey cells. Our primary goal is to characterize the properties of the viral template and the enzyme engaged in its transcription, and to learn what factors influence the interaction between the template and the enzyme, thereby controlling the rate of viral RNA synthesis. In earlier work, we have devised a procedure for the isolation of the SV40 transcription complex (VTC) from infected cells, and have begun to utilize the VTC to characterize the viral template and the process of transcription in vitro. The proposed experiments are described under three main topics: 1) the process of SV40 transcription; 2) the nature of the template for SV40 transcription; and 3) the control of SV40 gene expression. The first topic takes up the various stages in transcription, such as RNA chain elongation, and release, termination, and histone movement along the template. Purified SV40 transcription complex will be utilized in these experiments. The second topic concerns primarily the basis whereby recently replicated SV40 DNA serves preferentially as a template for transcription and replication. For the third topic, purified VTC from "early" and "late" stages of infection will be utilized to study factors which influence the rate of transcription of the two strands of SV40 DNA, and of the mRNA and non-mRNA regions of this genome.